[media] v4l2-ioctl: WARN_ON if querycap didn't fill device_caps

This is easy to forget to do in drivers. While v4l2-compliance will check for it,
not everyone remembers to run it. So warn about it.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
index 75658717961f..faac2f4e0f3a 100644
--- a/drivers/media/v4l2-core/v4l2-ioctl.c
+++ b/drivers/media/v4l2-core/v4l2-ioctl.c
@@ -1017,6 +1017,12 @@ static int v4l_querycap(const struct v4l2_ioctl_ops *ops,
         ret = ops->vidioc_querycap(file, fh, cap);
 
         cap->capabilities |= V4L2_CAP_EXT_PIX_FORMAT;
+        /*
+         * Drivers MUST fill in device_caps, so check for this and
+         * warn if it was forgotten.
+         */
+        WARN_ON(!(cap->capabilities & V4L2_CAP_DEVICE_CAPS) ||
+                !cap->device_caps);
         cap->device_caps |= V4L2_CAP_EXT_PIX_FORMAT;
 
         return ret;